N-benzyl-2-(3,5-dimethyl phenoxy)-2-alkoxy amide herbicides

ABSTRACT

N-benzyl-2-(3,5-dimethyl phenoxy)-2-alkoxy amide compounds having the formula ##STR1## in which R is hydrogen or alkyl and R 1  is alkyl; and their use as herbicides.

This invention relates to certain novel N-benzyl-2-(3,5-dimethylphenoxy)-2-alkoxy amides which are useful as herbicides.

The compounds of the present invention are new compositions of matterand correspond to the formula ##STR2## in which R is hydrogen or alkylhaving 1 to 4 carbon atoms, preferably methyl and R¹ is alkyl having 1to 4 carbon atoms, preferably 1 to 2 carbon atoms and more preferablyethyl.

In the above description of the compounds of this invention, alkylincludes both straight chain and branched chain configurations, forexample, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl ortert.-butyl.

The compounds of this invention are active herbicides of a general type.That is, they are herbicidally effective against a wide range of plantspecies. The method of controlling undesirable vegetation of the presentinvention comprises applying an herbicidally effective amount of theabove-described compounds to the area where control is desired.

An herbicide is used herein to mean a compound which controls ormodifies the growth of plants. By a "growth controlling amount" is meantan amount of compound which causes a modifying effect upon the growth ofplants. Such modifying effects include all deviations from naturaldevelopment, for example, killing, retardation, defoliation,dessiccation, regulation, stunting, tillering, stimulation, dwarfing andthe like. By "plants", it is meant germinating seeds, emergingseedlings, and established vegetation including the roots andabove-ground portions.

The compounds of the present invention can be prepared by the followinggeneral method: ##STR3##

Generally, a mole amount of the ester, a slight mole excess of thesuccinimide, and a few crystals of the peroxide are mixed in carbontetrachloride and heated to reflux for an hour. The mixture is thencooled and filtered and the filtrate is evaporated to leave an oil.##STR4##

The potassium t-butoxide is first dissolved in t-butyl alcohol, followedby addition of the phenol and finally the ester, the latter tworeactants approximately equal in molar quantity to the butoxide. In theensuing exothermic reaction, the potassium bromide separates from themixture which is subsequently poured into water and extracted withchloroform. ##STR5##

Generally, to a mole excess of the amine dissolved in a solvent alongwith a small amount of ethylene glycol is added the acetate. Withslurring the mixture is heated at 50° C for about 3 hours and theproduct is recovered and recrystallized by conventional means.

The example hereinafter illustrates a method of preparation of thecompounds of the invention.

EXAMPLE N-benzyl-2-methoxy-2-(3,5-dimethylphenoxy)acetamide ##STR6##

A mixture of 20.0 g (0.19 mole) methyl 2-methoxyacetate, 34.6 g (0.20mole) N-bromosuccinimide and a few crystals of benzoyl peroxide in 200ml carbon tetrachloride was heated to reflux. After an initial vigorousreaction, the mixture was heated for 1 hour, cooled, and filtered. Thefiltrate was evaporated at 15 mm pressure on a rotary evaporator toleave 34.0 g (98% yield) of an oil, n_(D) ³⁰ -- 1.4694, identified byNMR analysis as methyl 2-bromo-2-methoxyacetate.

Potassium t-butoxide, 21.5 g (0.18 mole), was dissolved in 150 mlt-butyl alcohol. The mixture was stirred for 15 minutes at roomtemperature. 22.0 g (0.18 mole) of 3,5-dimethylphenol was then added,followed by 32.0 g (0.18 mole) of methyl 2-bromo-2-methoxyacetate. Theaddition occurred at 35°-40° C. The reaction was exothermic withseparation of potassium bromide. After 3 hours of stirring with noexternal heating, the mixture was poured into 600 ml water and theresulting mixture was extracted with two 150 ml portions of chloroform.The extracts were combined and washed with three 150 ml portions ofsaturated sodium chloride solution. The solution was then dried overmagnesium sulfate and evaporated to leave 29.9 g of an oil, n_(D) ³⁰ --1.5013, identified by infrared spectroscopy asmethyl-2-(3,5-dimethylphenoxy)-2-methoxyacetate.

In a 300 ml flask were placed 2.7 g (0.03 mole) benzyl amine and 1 ml ofethylene glycol. To this was added 5.0 g (0.02 mole) of themethyl-2-(3,5-dimethylphenoxy)-2-methoxyacetate with stirring. Thetemperature rose to 31° C and then began to decrease. The mixture washeated at 50° C for 3 hours and was then allowed to cool to roomtemperature. The partially solidified product was dissolved in 100 mlbenzene and the resulting solution was washed with 3-100 ml portions ofwater. The solution was dried over magnesium sulfate and evaporated toleave a solid, 5.0 g which was recrystallized from hexane to give 3.8 gof a solid, m.p. 77°-79° C, which was identified by NMR spectroscopy tobe the desired product.

Other compounds, such as those included in the following table, can beprepared in a manner analogous to that taught in the examples above,using the appropriate corresponding materials.

The following is a table of certain selected compounds that arepreparable according to the procedure described hereto. Compound numbersare assigned to each compound and are used through the remainder of theapplication.

                  TABLE I                                                         ______________________________________                                         ##STR7##                                                                     Compound                                                                      Number    R          R.sup.1    m.p.                                          ______________________________________                                        1 *       H          CH.sub.3   77-79 ° C                              2         CH.sub.3   CH.sub.3   n.sub.D.sup.30 1.5425                         ______________________________________                                         * Prepared in Example                                                    

Herbicidal Screening Tests

As previously mentioned, the herein described compounds produced in theabove-described manner are phytotoxic compounds which are useful andvaluable in controlling various plant species. Selected compounds ofthis invention are tested as herbicides in the following manner.

Pre-emergence Herbicide Screening Test

Using an analytical balance, 20 mg of the compound to be tested isweighed out on a piece of glassine weighing paper. The paper andcompound are placed in a 30-ml wide-mouth bottle and 3 ml of acetonecontaining 1% Tween 20.sup.® is added to dissolve the compound. If thematerial is not soluble in acetone, another solvent such as water,alcohol or dimethylformamide (DMF) is used instead. When DMF is used,only 0.5 ml or less is used to dissolve the compound and then anothersolvent is used to make the volume up to 3 ml. The 3 ml of solution issprayed uniformly on the soil contained in a small flat one day afterplanting weed seeds in the flat of soil. A No. 152 DeVilbiss atomizer isused to apply the spray using compressed air at a pressure of 5 lb/sq.in. The rate of application is 8 lb/acre and the spray volume is 143gal/acre.

On the day preceding treatment, the flat which is 7 inches long, 5inches wide and 2.75 inches deep is filled to a depth of 2 inches withloamy sand soil. Seeds of seven different weed species are planted inindividual rows using one species per row across the width of the flat.The seeds are covered with soil so that they are planted at a depth of0.5 inch. The seeds used are hairy crabgrass (Digitaria sanguinalis),green foxtail (Setaria viridis), watergrass (Echinochloa crusgalli), redoat (Avena sativa), redroot pigweed (Amaranthus retroflexus), Indianmustard (Brassica juncea) and curly dock (Rumex crispus). Ample seedsare planted to give about 20 to 50 seedlings per row after emergencedepending on the size of the plants.

After treatment, the flats are placed in the greenhouse at a temperatureof 70° to 85° F and watered by sprinkling. Two weeks after treatment,the degree of injury or control is determined by comparison withuntreated check plants of the same age. The injury rating from 0 to 100%is recorded for each species as percent control with 0% representing noinjury and 100% representing complete kill.

Post-emergence Herbicide Screening Test

Seeds of six plant species, including hairy crabgrass, watergrass, redoat, mustard, curly dock and Pinto beans (l Phaseolus vulgaris) areplanted in the flats as described above for pre-emergence screening. Theflats are placed in the greenhouse at 70° to 85° F and watered dailywith a sprinkler. About 10 to 14 days after planting when the primaryleaves of the bean plants are almost fully expanded and the firsttrifoliate leaves are just starting to form, the plants are sprayed. Thespray is prepared by weighing out 20 mg of the test compound, dissolvingit in 5 ml of acetone containing 1% Tween 20.sup.® and then adding 5 mlof water. The solution is sprayed on the foliage using a No. 152DeVilbiss atomizer at an air pressure of 5 lb/sq. in. The sprayconcentration is 0.2% and the rate is 8 lb/acre. The spray volume is 476gal/acre.

The results of these tests are shown in Table II.

                  TABLE II                                                        ______________________________________                                        Herbicidal Activity - Screening Results                                       Compound    * Percent Control at 8 lb/A                                       Number      Pre-emergence  Post-emergence                                     ______________________________________                                        1           60             67                                                 2           59             60                                                 ______________________________________                                         * Average for seven plant species in the pre-emergence test and for six       plant species in the post-emergence test.                                

The compounds of the present invention are used as pre-emergence orpost-emergence herbicides and are applied in a variety of ways atvarious concentrations. In practice, the compounds herein defined areformulated into herbicidal compositions, by admixture, in herbicidallyeffective amounts, with the adjuvants and carriers normally employed forfacilitating the dispersion of active ingredients for agriculturalapplications, recognizing the fact that the formulation and mode ofapplication of a toxicant may affect the activity of the materials in agiven application. Thus, these active herbicidal compounds may beformulated as granules of relatively large particle size, as wettablepowders, as emulsifiable concentrates, as powdery dusts, as solutions oras any of several other known types of formulations, depending upon thedesired mode of application. Preferred formulations for both pre- andpost-emergence herbicidal applications are wettable powders,emulsifiable concentrates and granules. These formulations may containas little as about 0.5% to as much as about 95% or more by weight ofactive ingredient. The amount applied depends upon the nature of theseeds or plants to be controlled and the rate of application varies from1/8 to approximately 50 pounds per acre.

Wettable powders are in the form of finely divided particles whichdisperse readily in water or other dispersant. The wettable powder isultimately applied to the soil either as a dry dust or as a dispersionin water or other liquid. Typical carriers for wettable powders includefuller's earth, kaolin clays, silicas and other readily wet organic orinorganic diluents. Wettable powders normally are prepared to containabout 5 to about 95% of the active ingredient by weight and usually alsocontain a small amount of wetting, dispersing or emulsifying agent tofacilitate wetting and dispersion.

Emulsifiable concentrates are homogeneous liquid compositions which aredispersible in water or other dispersant, and may consist entirely ofthe active compound with a liquid or solid emulsifying agent, or mayalso contain a liquid carrier, such as xylene, heavy aromatic naphthas,isophorone and other non-volatile organic solvents. For herbicidalapplication, these concentrates are dispersed in water or other liquidcarrier and normally applied as a spray to the area to be treated. Thepercentage by weight of the essential active ingredient may varyaccording to the manner in which the composition is to be applied, butin general comprises about 0.5 to 95% of active ingredient by weight ofthe herbicidal composition.

Granular formulations, wherein the toxicant is carried on relativelycoarse particles, are usually applied without dilution to the area inwhich suppression of vegetation is desired. Typical carriers forgranular formulations include sand, fuller's earth, bentonite clays,vermiculite, perlite and other organic or inorganic materials whichabsorb or which may be coated with the toxicant. Granular formulationsnormally are prepared to contain about 5 to about 25% of activeingredient and may also contain small amounts of other ingredients whichmay include surface-active agents such as wetting agents, dispersingagents or emulsifiers; oils such as heavy aromatic naphthas, kerosene orother petroleum fractions, or vegetable oils; and/or stickers such asdextrins, glue or synthetic resins.

Typical wetting, dispersing or emulsifying agents used in agriculturalformulations include, for example, the alkyl and alkylaryl sulfonatesand sulfates and their sodium salts; polyhydric alcohols; and othertypes of surface-active agents, many of which are available in commerce.The surface-active agent, when used, normally comprises from 0.1 to 15%by weight of the herbicidal composition.

Dusts, which are free-flowing admixtures of the active ingredient withfinely divided solids such as talc, clays, flours, and other organic andinorganic solids which act as dispersants and carriers for the toxicant,are useful formulations for soil-incorporating applications.

Pastes, which are homogeneous suspensions of a finely divided solidtoxicant in a liquid carrier such as water or oil, are employed forspecific purposes. These formulations normally contain about 5 to about95% of active ingredient by weight, and may also contain small amountsof a wetting, dispersing or emulsifying agent to facilitate dispersion.For application, the pastes are normally diluted and applied as a sprayto the area to be affected.

Other useful formulations for herbicidal applications include simplesolutions of the active ingredient in a dispersant in which it iscompletely soluble at the desired concentration, such as acetone,alkylated naphthalenes, xylene or other organic solvents. Pressurizedsprays, typically aerosols, wherein the active ingredient is dispersedin finely divided form as a result of vaporization of a low boilingdispersant solvent carrier, such as the Freons, may also be used.

The phytotoxic compositions of this invention are applied to the plantsin the conventional manner. Thus, the dust and liquid compositions canbe applied to the plant by the use of power-dusters, boom and handsprayers and spray dusters. The compositions can also be applied fromairplanes as a dust or a spray because they are effective in very lowdosages. In order to modify or control growth of germinating seeds oremerging seedlings, as a typical example, the dust and liquidcompositions are applied to the soil according to conventional methodsand are distributed in the soil to a depth of at least 1/2 inch belowthe soil surface. It is not necessary that the phytotoxic compositionsto be admixed with the soil particles since these compositions can alsobe applied merely by spraying or sprinkling the surface of the soil. Thephytotoxic compositions of this invention can also be applied byaddition to irrigation water supplied to the field to be treated. Thismethod of application permits the penetration of the compositions intothe soil as the water is absorbed therein. Dust compositions, granularcompositions or liquid formulations applied to the surface of the soilcan be distributed below the surface of the soil by conventional meanssuch as discing, dragging or mixing operations.

The phytotoxic compositions of this invention can also contain otheradditaments, for example, fertilizers, pesticides and the like, used asadjuvants or in combination with any of the above-described adjuvants.Other phytotoxic compounds useful in combination with theabove-described compounds include, for example,2,4-dichlorophenoxyacetic acids, 2,4,5-trichlorophenoxyacetic acid,2-methyl-4-chlorophenoxyacetic acid and the salts, esters and amidesthereof; triazine derivatives, such as2,4-bis(3-methoxypropylamino)-6-methylthio-s-triazine,2-chloro-4-ethylamino-6-isopropylamino-s-triazine, and2-ethylamino-4-isopropylamino-6-methylmercapto-s-triazine; ureaderivatives, such as 3-(3,4-dichlorophenyl)-1,1-dimethyl urea and3-(p-chlorophenyl)-1,1-dimethyl urea; and acetamides such asN,N-diallyl-α-chloroacetamide, and the like; benzoic acids such as3-amino-2,5-dichlorobenzoic; thiocarbamates, such as S-propyldipropylthiocarbamate, S-ethyl dipropylthiocarbamate, S-ethylcyclohexylethyl thiocarbamate, S-ethylhexahydro-1H-azepine-1-carbothioate and the like;4-(methylsulfonyl)-2,6-dinitro-N,N-substituted anilines, such as4-(methylsulfonyl)-2,6-dinitro-N,N-di-n-propyl aniline,4-trifluoromethyl-2,6-dinitro-N,N-substituted anilines, such as4-trifluoromethyl-2,6-dinitro-N,N-di-n-propyl aniline and4-trifluoromethyl-2,6-dinitro-N-ethyl-N-n-butyl aniline. Fertilizersuseful in combination with the active ingredients include, for example,ammonium nitrate, urea and superphosphate. Other useful additamentsinclude materials in which plant organisms take root and grow such ascompost, manure, humus, sand and the like.

The concentration of a compound of the present invention, constitutingan effective amount of the best mode of administration in the utilitydisclosed is readily determinable by those skilled in the art.

It is claimed:
 1. The method of controlling undesirable vegetation whichcomprises applying to the area where control of said vegetative growthis desired, an herbicidal amount of a compound having the formula##STR8## in which R is hydrogen or alkyl having 1 to 4 carbon atoms andR¹ is alkyl having 1 to 4 carbon atoms.
 2. The method of claim 1 inwhich R is methyl and R¹ is methyl.
 3. The method of claim 1 in which Ris hydrogen and R¹ is methyl.